Yaesu FT-857D Operating Manual

Also see for FT-857 series: Manual Technical supplement Operation manual Brochure & specs Technical supplement

Contents

Yaesu FT-857D Operating Manual Manual pdf 12 page image

10 FT-857 Operating ManualGROUNDINGThe provision of an effective ground system is important in any successful communicationsstation. A good ground system can contribute to station efficiency in a number of ways:r It can minimize the possibility of electrical shock to the operator.r It can minimize RF currents flowing on the shield of the coaxial cable and the chassis ofthe transceiver which may cause interference to nearby home entertainment devices orlaboratory test equipment.r It can minimize the possibility of erratic transceiver operation caused by RF feedback orimproper current flow through logic devices.An effective earth ground system may take several forms; for a more complete discussion,see an appropriate RF engineering text. The information presented below is intended only asa guideline.Inspect the ground system – inside the station as well as outside – on a regular basis so as toensure maximum performance and safety.Mobile Station GroundingAlthough satisfactory grounding in most installations will be achieved via the DC cable’snegative lead and the antenna system’s coaxial cable shield, it is often recommended thatyou provide a direct ground connection to the vehicle chassis at the mounting location of thetransceiver (installation using the MMB-82 Mounting Bracket will accomplish this, if theMMB-82 itself is mounted to the vehicle’s chassis). Due to unexpected resonances whichmay naturally occur in any location, improper communication system performance mayresult from insufficient grounding. These symptoms may include:r RF feedback (resulting in distortion on your transmitted signal);r Unintended frequency change;r Blinking or blanking of the frequency display;r Noise pickup; and/orr Loss of memory.Note that these conditions may occur in any communications installation. The FT-857 in-cludes extensive filtering designed to minimize the chance of such problems; however, ran-dom currents set up by insufficient RF grounding can nullify such filtering. Bonding the rearpanel Ground lug of the FT-857 transceiver to the vehicle or vessel’s ground system shouldclear up any such difficulties.Vertex Standard does not recommend the use of “on glass” mobile antennas unless the shieldof the coaxial cable is securely grounded near the feedpoint of the antenna. Such antennasfrequently are responsible for the ground-related difficulties described above.INSTALLATION